This prospective pilot study is designed to explore the relationship between injury-related physical, immunologic, and psychologic variables and specific injury-related outcomes. The research questions guiding this study are: 1. What is the influence of type of injury, injury severity, and immune status on survival following traumatic injury requiring massive transfusion? and 2. What is the influence of type of injury, injury severity, immune status, and psychological distress on length of stay, number of complications, and functional recovery? A sample of 25 individuals, sustaining traumatic injury requiring greater than 10 units of packed red blood cells within the first 24 hours after injury will be enrolled in the study. Subjects will be followed longitudinally for 3 months. Data will be collected: after injury but before resuscitation commences (T1), 2 days (T2), 7 days (T3), 1 month T4), and 3 months (T5). Data collected includes venous blood samples fo immune phenotypes (T1, T2, T3, T5) and hepatitis serology (T1, T4, T5); survival, complications, length of stay (chart audit at T5); type of injury and injury severity from computerized trauma registry (T5); and structured interviews for psychological distress (T3, T4, T5) and functional recovery (T5). Data will be analyzed using descriptive statistics and bivariate analysis. Results from this pilot study will provide preliminary data to determine the feasibility of a large scale study of the influence of injury-related physical, immune and psychologi variables on selected outcomes following life-threatening injury requiring massive transfusion. Subsequent studies will focus on the development and testing of interdisciplinary interventions to improve survival, minimize secondary complications, control length of stay and costs, and enhance functional recovery following life-threatening injuries.